In order to provide a more durable surface for vehicular traffic, modern roadways are usually paved. In the construction of new roadways, pavement is typically applied to an unpaved base after it has been graded and compacted (i.e., the new roadway is surfaced). In the repair of existing roadways, however, pavement is typically applied to the surface of the existing roadway (i.e., the existing roadway is resurfaced).
Over time, existing roadways inevitably become worn and in need of repair. For example, cracks may develop in the surface and/or the surface may become overly smooth. In either event, the existing roadway surface becomes dangerous to drive on and, thus, presents a public safety concern. If cracks develop, the surface will no longer be water resistant, and the roadway will deteriorate at an accelerated pace. If, on the other hand, the surface becomes overly smooth, the skid resistance of the roadway will be adversely effected. As such, existing roadways should be periodically resurfaced (or repaved) in the course of proper maintenance.
Depending on the application of the roadway, pavements may either be of flexible or rigid construction. Rigid pavements are typically formed of concrete, or the like, while flexible pavements typically comprise a combination of aggregate material (e.g., gravel, sand, crushed stone, etc.) and adhesive material (e.g., liquid asphalt, emulsified asphalt, molten bituminous material, binder material, etc.).
A common process for paving a roadway with flexible pavement is known as "chipsealing". In chipsealing, loose aggregate material is dropped into a previously applied layer of adhesive material which binds the aggregate material to a surface (e.g., the unpaved base of a new roadway or the surface of an existing roadway). In practice, chipsealing utilizes an asphalt distributor and a chipspreader. The asphalt distributor is used to apply an initial layer of adhesive material to the surface, and, once the adhesive material is in place, the chipspreader is then used to distribute aggregate material on top of the initial layer of adhesive material. Thus, in practice, chipsealing is performed by two separate machines making two separate passes over the same portion of the roadway in order to apply a single layer of pavement to that portion.
By and large, chipsealing is a relatively fast and inexpensive technique for surfacing or resurfacing a roadway. However, presently-employed chipsealing processes have several noted deficiencies. First, two separate machines are required (i.e., an asphalt distributor and a chipspreader). Second, two separate passes over the same portion of roadway is needed to complete each layer of the paving operation (i.e., an initial pass by the asphalt distributor and a subsequent pass by the chipspreader). Third, since the loose aggregate material must submerse into the previously applied layer of adhesive material in order to properly bond therewith, the maximum thickness of each pavement layer is limited to the size of the largest individual piece of aggregate material (e.g., the largest stone). As a result, only relatively thin layers of pavement may be formed, and, if a greater thickness is desired, additional layers of pavement must thereafter be applied.
In addition to the shortcomings noted above, it is also found that presently-employed chipsealing processes often leave loose particles of aggregate material on the freshly paved roadway surface. More particularly, it has been found that many particles of aggregate material do not sufficiently submerse into the underlying adhesive material or bond therewith. This is particularly true for top level particles. In addition, other particles weakly bond with the adhesive material, and as a result, are often dislodged when vehicles drive over the roadway. Loose aggregate material also gives the freshly paved roadway surface a peculiar non-black appearance.